DE1915061B2 - CONDUCTIVE PLASTIC MASS FOR THE CABLE SECTOR - Google Patents

Description

The invention relates to the use of a mixture of

a) 50 to 36 percent by weight isotactic polybutene-1,

b) 23 to 29 percent by weight of amorphous or atactic thermoplastic material as well

c) 27 to 35 percent by weight of a conductive carbon black as a conductive plastic mass for the Cable sector.

Such masses are used for. B. as conductor smoothing compounds and have the task of an intermediate layer between train the metallic inner conductor and the insulation of a high-voltage cable, which voltage levels and to prevent glow discharges at the interfaces. Rs is also desired to be a use such a mass in combination with isotactic polybutene-1 as a cable outer jacket in order to Discharge external currents, for example for grounding a telephone cord. This means that such a mass must be electrically conductive, but at the same time the various mechanical properties that are placed on the insulation.

Gs is known to be made of special conductive masses Ethylene copolymers, especially ethylene acrylate resins, and to produce so-called carbon blacks (Polymer-Engineering and Science 7, p. 63 to 70 [1967]). However, these are not very suitable because they lead to stress cracking when exposed to current tend, and especially with insulating materials that are particularly resistant to stress cracking, such as the one that can be used in this regard Polybutene-1, cannot be welded or only very imperfectly, what a flawless one Functioning of the cables is a matter of course.

To partially crystalline polybutene-1 as an insulating jacket To be able to use it, it is obviously necessary to also use a conductive material on the same basis with a specific volume resistance of less than 1000 U cm.

A carbon black additive, as found in the

ίο USA.-Patent 3 257 351 and the German Auslegeschrift 1 226 782 is known in principle for partially crystalline polyolefins. Here you get, depending on The type and amount of carbon black and the polymer, especially with higher amounts of carbon black, is a stiffened one Starting material (French patent specification 1445962, U.S. Patent 3,385,817). An associated fragility is sought through networking or to be lifted by irradiation, or low-crystalline polypropylenes of certain lower ones should be used Use molecular weights that are not marketable because of their other unfavorable properties (U.S. Patents 3,325,442 and 3,264,253). If you now process Polybutene-1 with the required If you have a lot of soot, you get, as expected, a mass that is far too inflexible and too susceptible to breakage is. If you try to add non-crystalline substances, such as those used for humiliation des Brittle Point of istotactic polypropylene were proposed (German interpretation

Documents 1 145 791, 1 124 239, 1 104694 and 1 254862). however, it turns out that when 10 is replaced, 20, 30 and 40 percent by weight of the crystalline component in one of isotactic polybutene-1 and 24 percent by weight Conductivity black existing and on

a specific volume resistance below 1000 U cm, for example 200 μl cm. adjusted mixture by equivalent amounts of non-crystalline amorphous or atactic substances (atactic polybutene-1, atactic polypropylene, ethylene-propylene rubber, polyisobutylene) a considerable, ie far beyond 1000 Li cm. Increase in the specific volume resistance occurs. An increase in the proportion of soot in turn results in a further decrease in the flexibility gained, so that a solution based on this does not appear to be given.

It is known from French patent specification 1,184,742, isotactic and atactic polybutene-1 to mix with carbon black to form a thermoplastic mass, but the masses obtained are suitable only for the production of leather-like foils; the lower mentioned molecular weight of the isotactic polybutene-1 as well as the far too little amount of soot could not solve the problem that dominates here contribute to the broad, named proportion of atactic Polymers required an unobvious, very strict choice, and from the fact that carbon black was used as a is regarded as an inert filler, one could not contribute to its decisive property conversion other composition close.

The object of the present invention is, despite the difficulties described, a conductive To find plastic compound for the cable sector based on polybutene-1, which is based on the expected good compatibility with conventional polybutene-1 would finally enable the excellent To make properties of this polymer more accessible to the cable sector.

I) IL-SL task is achieved through the use of a Mix of

al M) up to 36 percent by weight istotactic polybutene 1,

b) 23 to 29 percent by weight of amorphous and / or mactic thermoplastic material as well

ei. 7 to 35 percent by weight of a conductivity liquid solved as a conductive plastic compound for the cable sector.

Useful isotactic polybutenes-1 are t.eilkrisL.llin and have, ",. j-values *) from 2 to 6 and Density according to DIN 53479 from 0.900 to 0.930. They are manufactured using the Ziegler-Natta process wnk-r use of complex catalyst systems. »■ ie of the contact

Al (C ₂ H ₅ I ₂ CTOTiCl., AlCl _{1 I.}

Atactic polybutene-1, which can be used, is obtained by the same polymerization process as an ether-Kisheher fraction of up to about 21) percent by weight. It therefore does not need to be separated for the present case, but must be taken into account when adding the further required amounts of atactic or amorphous phase with regard to the established limits. earth. The " _lred " values of the atactic material - and the same applies also to the atactic polypropylene "material obtained during the polymerization of isotactic polypropylene - are between U.3 and 0.9, preferably 0.5 to 0.7.

Suitable ethylene-propylene rubbers which are produced as amorphous copolymers using complex catalyst systems such as VCl ₄ , VCl ₃ or VOCl ₃ and aluminum alkyls or aluminum alkyl halides, e.g. B. aluminum sesquichloride, prepared at temperatures above 0 C, preferably between 20 and 60 C, have molecular weights between 70,000 and 250,000 with a propylene or ethylene content of 20 to 80 percent by weight.

Polyisobutylenes which can be obtained by cationic polymerization, for example with the aid of BF complexes as initiators in more liquid ethylene at about -1 (X) ¹ C, are those with molecular weights between 400,000 and 5,000,000

The carbon blacks are, on the one hand, carbon blacks obtained by thermal decomposition of acetylene gas (acetylene carbon blacks) with average particle sizes of 30 to 60, preferably 35 to 57 πΐμ, determined by electron microscopy, and specific surface areas of 95 to 53, preferably 90, calculated from this up to 56 m ² g and contents of volatile constituents not more than 1 percent by weight, on the other hand to furnace carbon blacks obtained by the process of incomplete combustion of liquid hydrocarbons (oils) with mean particle sizes determined by electron microscopy of 20 to 29, preferably 22 to 28 ηΐμ, as well as corresponding -

*) 'iwrWcrt: The reduced viscosity i) _{tti is} calculated according to the formula

1 ¹ Ii - 'a>

where c = concentration (c = 0.1 in p-xylene at 110 ° C.); q, = dynamic viscosity of the solution; > _to = dynamic toughness of the I rWtune mean.

Dating specific surface areas of 140 to 85, preferably 120 to 89 nr / g with a content of volatile constituents do not exceed 2, usually between 1 and 2 percent by weight. It is about in both cases it is about highly structured carbon blacks, whereby the acetylene carbon blacks have a structure index (see Rubber Age 55, P. 475, No. 5, August 1944) around 300, the Furnuce carbon blacks have such around 130. The smaller the diameter of the soot particles and the larger the specific one The surface, the better the conductivity in general, but usually the greater also the loss of flexibility of the resulting mixture. In any case it is of considerable influence the amount of volatile substance, insofar as higher contents of volatile constituents the conductivity are able to greatly impair.

Conductive plastic compounds made from these components meet the requirements if at a soot dosage of 26 to 35 percent by weight

ίο the proportion of atactic and / or amorphous phase on the one hand, does not fall below 23 percent by weight of the total mixture and, on the other hand, does not exceed 29 percent by weight. If the proportion of soot is greater than 35 percent by weight or the proportion of

If atactic and / or amorphous material is less than 23 percent by weight, the result is masses that are too brittle for the intended use. If the Rußanteii smaller than Ti weight percent and the proportion of atactic and / or amorphous phase is greater than 29 percent by weight, the specific on-resistance is well over 1000 cm ii, indeed sometimes several orders of magnitude higher. Line Lowering the crystalline proportion of the mixture below 36 percent by weight also results in too great a loss of strength.

For the purpose of stabilization one sets deii Crowds expedient rider! i "antioxidants too. like Jonol = (2- .6-Di-t-butyl-p-cresol). 2-u-methylcyclohexyl-4.-6-dimethylphenol, N-stearyl-p-aminophenol or 4-, 4 -thio-bis- (6-t-butyl-3-methyl-

phenol), optionally together with sulfur-containing compounds such as dilauryl thiodipropionate in Concentration from 0.03 to 0.5 percent by weight. You can also use lubricants such as calcium. Natnum- or zinc stearate (0.1 to 0.6 percent by weight) / exposure, Lubricants such as graphite (1 to 5 percent by weight) and from isotactic material, so to speak introduced crystallization and conversion accelerators for a faster transition of the modification II obtained from the melt of isotactic Polvbuten-1 into the stable modification I (J Polymer Sci. B 62, 870 [19621). / B. Amyl acetate. <(- chloronaphthalene and phenyl ether, furthermore ester plasticizers known from PVC, such as dioctyl phthalate, optionally also in combination

mi! The latter left isotactic polypropylene at the expense of the crystalline polybutene-1 component of the mixture or substances known as viscous genes in the form of aromatic, partially aromatic or aliphatic hydrocarbons.

The production of the masses, for which protection is not sought, can be ^{done most easily using a roller heated to about 120 to 160 °} C., for example by inserting into the one placed on this roller for a case

plasticized, partially crystalline polybutene-1 atactic and / or amorphous material, carbon black and other additives such as antioxidants, lubricants, etc. incorporated. One makes use of it in a particularly advantageous manner

5 '6

but one parts heated to about 140 to 18 (TC) aUiktisches Polybutene-1, 30 parts by weight acetyl kneader and brings the plastic len carbon black produced in this and 45 parts by weight of isotactic poly mixture aui a butene-oil heated to about 100 to 120 C, which the stabilizing and processing roller, feeds out to a case which is contained in strips in turn. Man cuts, which latter one takes from a mill or 5, the mixture after 5 minutes of mixing time fed to a granulator for comminution. This pulls it on a roller mill heated to 120 ° C The granules produced can then easily be turned into a skin and pressed into 2, 3 and an extruder for sheets 4 mm thick from the feed hopper to the nozzle, temperatures set to about 100 to 200 ° C

conductive sheath masses are processed. The io result of the exams

The following examples are based on the invention. Specific volume resistance 210 U cm

clear. Bending limit stress 100 kp / cm ²

Here, a cbjekt.ven comparison _{Qh Br} * _ch ^H _{at W (} 4 _re r

permitted, the following substances are always used: _D ,, ·

Isotactic polybutene! of its atactic .5 notched impact strength without fracture

ethereal phase freed and with a density ßriuleness temperature - S ^a C

according to DIN 53479 from 0, <J15, an , lnt of 4.5, welding _{factor 09 to 1}

corresponding to an average MKG of 2,200,000, scnweiuiajcior

a limit bending stress - measured on aas 4-mm- A use of atactic polyp ropylene in place

Standard small bars punched out from press plates according to 20 of atactic polybutene-1 led to practical

DIN 53452 - of 240 kp / cm ² , a notched impact equal results.

Toughness test according to DIN 53453 "without break"

and a Brittleness temperature according to ASTM D 746 comparative example 1 b)

Atactic polybutene-1 of ",," - value 0.6, ent- 25 ") With one of 25 parts by weight atakliscjiem

Speaking about an average molecular weight of polybutene-1, 37 parts by weight of acetylene black and

of 300,000. 38 parts by weight of isotactic polybutene-1 according to

Stabilizing and processing aids are, la) existing mixture is referred to as in the above to 100 parts by weight of the total mixture, proceed as described in the previous example. 0.4 parts by weight 4-, 4'-thio-bis- (6-t-butyl-, 3-methyl- 30 The following data are obtained: phenol) 0.3 parts by weight of dilauryl thiodipropionate 04 Weight point calcium stearate. resistance 170 U cm

Acetylene black with an average particle size limit bending stress of 150 kp / cm ²

(determined by electron microscopy) of 35 πΐμ, one _{Mjt Brucb} ^ ei further

specific surface of 90 m ² / g and a content of 35 deflection

of volatile constituents less than 0.6% notched impact strength 2 cmkp / cm ²

Furnace carbon black with an average particle size of Brittleness temperature + 18 ° C

23 iTifA, a specific surface area of? 3 m7g and a welding factor of 0.6 to 0.8

a volatile component of 2%.

Polyisobutylene with a molecular weight of 4,700,000. 40 The increase in susceptibility to breakage compared to

Ethylene-propylene rubber with a medium mixture 1 a) is unmistakable.

Molecular weight of 100,000 for a propylene Ii) If the amount of carbon black is reduced to a proportion of 50 percent by weight. retention of the atactic weight proportion of

The test method used is mixture 1 a) to 25 parts by weight and increases the

, ._, ^. .,, 45 crystalline component corresponding to 50 ge

the specific throughput _{resistance measured by weight <the following} results are obtained: on 2 mm panels according to DIN 53482 / VDE 0303,

Part 3, Specific Passage

the limit bending stress according to DIN 53452. Resistance 9000 U cm

the notched impact strength test, corresponding to the limit bending stress 80 kp / cm ²

DIN 53453, carried out on 3 mm plates, ⁵ ° without breakage on further

Brittleness temperature according to ASTM D 746. Deflection:

γλ tu rir 1. <o 1. f u η * Notched impact strength without fracture

The welding factor (He.zspiegel butt welding) Brittieness Temoeratur -12 C

is determined from the Zugfest.gke.t with reference to ihweSktor 09 Ws 1

the welded seam specimen (= 100%) in a 55 ^ cnweiuraicior

Temperature range from 180 to 240 ⁰ C with a Although in this case corresponds to the mechanical

Contact pressure on the mirror of 0.5 kp / cm ² and a property profile that of a conductor gloss compound

Welding pressure of 1 and 2 kp / cm ² . requirements. The specific through

The expression "ladder smoothing compound" includes a contact resistance, however, is more than one

»Semiconducting flexible-soft plastic compound«, the 60 power of ten too high in this specification, of course, everywhere

can be used where it is a question of comparative example Ic) Discharge currents, for example for grounding

of a telephone cable al? Outer cable sheath. a) Put into the Werner & Pfleiderer kneader

65 20 parts by weight of atactic polybutene-1, 30 parts

Example la) parts by weight of acetylene black and 50 parts by weight of iso-

One brings tactical polybutene-1 into a heated to 130 "C and proceeds as in

i-l kneader (Svstem Werner & Pfleiderer) 25 weight example 1 a \

The test specimens produced from the press plates show the following values:

Specific volume resistance 180 U cm

Limit bending stress 140 kp / cm ²

With a break in another
Deflection:

Notched impact strength 1.5 cmkp / cm ²

Brittleness temperature + 10 ⁰ C

Welding factor 0.9 to 1

/ {) Test specimens containing 30 parts by weight of acetylene black, 30 parts by weight of atactic and 40 parts by weight of isotactic polybutene -1, give the following results:

Specific volume resistance 1500 12 cm

Limit bending stress 90 kp / cm ²

Without breaking any further
Deflection:

Notched impact strength without breakage

Brittleness temperature - 12 ° C

Welding factor 0.9 to 1

Comparative examples 1 c), 1) and 1 c), β) make it clear what a great influence the atactic material exerts on the electrical and mechanical behavior and how narrow the range is in which satisfactory compounds are obtained for smoothing conductors or cable sheathing will.

Example 2

The atactic polybutene-1 in the formulation according to Example 1 a) is exchanged on the one hand for polyisobutylene and on the other hand against ethylene-propylene rubber and otherwise proceeds as there described.

The following property values are found in the case of polyisobutylene:

Specific volume resistance 180 L). cm

Limit bending stress 70 kp / cm ²

Without breaking any further
Deflection:

Notched impact strength without breakage

Brittleness temperature - 15 ° C

Welding factor 0.9 to 1

In the case of ethylene propylene rubber:

Specific volume resistance 170 Ω cm

Bending limit stress 80 kp / cm ²

Without break in · further
Deflection:

Notched impact strength without breakage

Brittleness temperature -25 ° C

Welding factor 0.9 to 1

Example 3

Instead of the acetylene black in Example 1 a), a furnace black is used instead of the atactic one Polybutene] an equal amount of polyisobutylene: in.

The dates are:

Specific volume resistance 150 12 cm

Bending limit stress 50 kp / cm ²

Without breaking any further

Deflection:

Notched impact strength without breakage

Brittleness temperature -32 ¹ C

Welding factor 0.9 to 1

Example 4

Using a tandem extrusion line, consisting of a) a Troester 60 extruder with

ro Short compression screw (20 D. compression ratio 1: 3.5) and a pressure spray head, right-angled to the extrusion axis, for the purpose of applying the conductor smoothing [recipe according to Example 1 a)] to the Metal cores and b) from a 150 Troester extruder with a short compression screw with the same compression ratio as above and one for Extrusion axis inclined by 60 ° for the coating with the insulating layer isotactic polybutene-1 of the specification made under la), one places several hundred meters to the Construction of a three-core 30 kV cable under the following processing conditions:

To a) conductor smoothing:

Temperature stirring 140/185/170/170/180 ^c C

'from the feed hopper
to the nozzle)

Melt temperature about 180 "C

Current consumption 24 A

Screw speed .... 23 rpm

Under these conditions, the conductor smoothing layer is 1 mm thick.

To b) core insulation:

Temperature control .... 155/155/165/150/156 C (from the feed hopper

to the nozzle)

Melt temperature about 205 X

Current consumption 160 A.

Screw speed .... 25 rpm
Take-off speed 3.2 m / min
water bath

(about 30 m long) .... temperature

at the 4OX input,
at output 20X

The thickness of the core insulation is 18 mm.
Loss factor measurements according to DIN 53 483 / V _L ! E 0303. Part 4, with voltages between 8 and 46 kV applied to the finished cable between the inner and outer conductors and over 270 hours at 500 Hz and 10 kV after the test lengths have been stored for 14 hours at room temperature ( The latter test is to be evaluated as a time-lapse method so that the results determined at 500 Hz and 270 hours correspond to those at 50 Hz and 2700 hours) confirm the expected result of a largely constant, i.e. independence of the loss angle f> from voltage and time.

If in example 1 a) the acetylene black is replaced by the furnace carbon black of example 3, one gives a from 38 weight percent isotactic. 28 weight percent atactic polybutene-1 and 34 weight percent Furnace-soot existing mixture results in comparable results. The same goes for example 2. if instead of 25 percent by weight ethylene propylene rubber, 45 percent by weight isotactic polybutene-1 and 30 percent by weight acetylene black now 23 percent by weight ethylene propylene rubber,

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49 percent by weight isotactic polybutene-1 and 28 percent by weight furnace carbon black can be used. Finally, in Example 3, the polyisobutylene is replaced by an ethylene-propylene rubber with a MW of 120,000 with a proportion of 40 percent by weight Propylene on the one hand and through the atactic material according to Example 1 on the other half result also values comparable to example 3.

Even when using polyisobutylene with molecular weights of 2,700,000 or 1,300,000 Place of a polyisobutylene with a MW of 4,700,000 according to Example 3 or also when exchanged of the partially crystalline poly-n-butylene in these examples against a higher or lower molecular weight product ('/ rfrf = 3.0 or 5.5) are not worth mentioning Received deviations.

^7th

Claims (7)

Patent claims: 1. Use a mixture of a) 50 to 36 percent by weight of isotactic polybutene-1, b) 23 to 29 percent by weight of amorphous and / or atactic thermoplastic material as c) 27 to 35 percent by weight of a conductivity black as a conductive plastic compound for the cable sector. 2. Use according to claim 1, characterized in that component b) is an atactic one Is polybutene-1. 3. Use according to claim 1, characterized in that component b) is an atactic Is polypropylene 4. Use according to claim 1, characterized in that component b) is an ethylene-propylene rubber is. 5. Use according to claim 1, characterized in that component b) is a polyisobutylene is. 6 Use according to claim 1, characterized in that that component c) is an acetylene black. 7. Use according to claim 1 to 5, characterized in that component c) is a furnace RuR is.